Trichlorosilane (SiHCl3), which is used as a raw material for the production of highly pure silicon (Si), can be produced by conversion through a reaction of silicon tetrachloride (SiCl4: tetrachlorosilane) with hydrogen.
In other words, silicon is produced by the reductive reaction and the thermolysis reaction of trichlorosilane represented by reaction schemes (1) and (2) shown below, and trichlorosilane is produced by the conversion reaction represented by reaction scheme (3) shown below.SiHCl3+H2→Si+3HCl   (1)4SiHCl3→Si+3SiCl4+2H2   (2)SiCl4+H2→SiHCl3+HCl   (3)
As an apparatus for producing trichlorosilane, for example, Patent Document 1 proposes an apparatus in which a plurality of heaters made of carbon are provided inside a reactor and these heaters made of carbon are directly energized and heated; thereby, heating a feed gas introduced to the reactor which contains hydrogen and silicon tetrachloride and converting the feed gas into trichlorosilane. In addition, a silicon compound such as silicon carbide is coated on the surface of this heater made of carbon. In other words, by protecting carbon with the coating film containing a silicon compound, the generation of impurities such as methane, methylchlorosilane, silicon carbide, and the like by the reaction of carbon with hydrogen, chlorosilane and hydrogen chloride in the feed gas and the reaction product gas can be prevented.
The following problems remain in the prior art described above.
In the above technique disclosed in Patent Document 1, silicon carbide or the like is coated on the surface of a heater made of carbon in order to prevent the generation of impurities. In this case, there were problems that the cost of the constituent members increased, and also the long-term usage of the heater could not be realized since the coating film of silicon carbide or the like was gradually etched to deteriorate.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. S62-123011